Adding secondary via rs.add on MongoDB

Question

I have a master and slave on Linux (centOS 7). The rs.initiate(cfg) was done, but its shows the below output when trying to add secondary via rs.add:

genienational:PRIMARY> rs.add("localhost.localdomain:27017")  
{  
     "ok" : 0,  
     "errmsg" : "The hosts test.appraisergenie.com:27017 a  
nd localhost.localdomain:27017 all map to this node new co  
nfiguration version 2 for replica set genienational",  
     "code": 103  
}  
genienational:PRIMARY> use local  
switched to db local  

How do I resolve?

Version: The master is on Enterprise. I think 3.2 and the slave is on 2.6.

Answer 1

The error message in your screenshot indicates you are trying to add identical members to your replica set under different names:

"The hosts x:27017 and y:27017 all map to this node in new configuration".

If you want to configure multiple replica set members on a single machine for testing purposes, all members need to use different ports and/or IP addresses.

Version: The master is on Enterprise. I think 3.2 and the slave is on 2.6.

Mixed-version replica sets are only supported for consecutive major versions (i.e. 3.2 and 3.0) and expected to be used transiently during a rolling upgrade to a new major version of MongoDB. A mixed replica set with 3.2 and 2.6 members is definitely not supported.